STATE OF VAPOUR SUBSISTING IN THE ATMOSPHERE. 



211 



The elasticity or expanfive force of pure vapour has been Elafticity of 

 examined at every fifth degree of Reaumur above Oto 110°. lectures above 

 by Mr. Betancourt, and may befeen in an excellent work of freezing. 

 Prony's, his Architecture Hydraulique, he has by a mod ingeni- 

 ous calculation interpolated the expanfions anfwering to the in- 

 termediate degrees. But Mr. Schmidt feems to have deter- 

 mined this expanfive force ftiltmore exa&ly than Betancourt. 

 Hence I here infert his table, adding Farenheit' s for Reaumur's 

 degrees, and diftinguilhing the expanfions interpolated by cal- 

 culation from thofe actually obferved by /. The forces are mea- 

 fured by the elevation of a mercurial column in inches and 

 hundreds of a French inch *. 



* The Paris cubic inch =r 1,21 Englifli. Now the Englifli cubic 

 inch of mercury when its fpecific gravity is 13,6 weights 3443,2' 

 Engliih grains, therefore the Paris inch weighs 4 1 86 Englifli grains, 

 and 1 1 ^ of this inch — 418,6grs : and T -| T of this inch41,86 grains. 



P2 



Note. 



